The present invention relates to a solar activated aeration system for introducing oxygen at a predetermined depth into a body of water.
In order to sustain marine life in lakes, ponds and other bodies of water, a sufficient quantity of oxygen in the water is essential. Generally, oxygen enters water primarily from the atmosphere through a combination of diffusion and turbulent mixing. The oxygen, occurring as dissolved O.sub.2 is; however, only moderately soluble in water, and its solubility decreases as temperature increases. This causes serious depletion of oxygen in water during hot summer months.
It will be apparent that an increase in organic matter production by algae and plants in a body of water causes greater demand on dissolved oxygen in the water as the organic matter decomposes at the termination of life cycles. Because of this, the deeper waters in a body of water may become entirely depleted of oxygen, thereby destroying fish habitat and possibly leading to the elimination of desirable species.
Serious oxygen deficiencies are most likely to occur when there is a combination of high temperature and little wind, along with decaying organic materials. There is also the possibility that summer storms with high winds may cause a pond to "turn over" -- mixing oxygen-deficient water from the bottom of the body of water with the surface water, thus further depleting the oxygen supply. During winter, ice and snow covering the body of water may also cause the oxygen levels to be low.
Substantial quantities of dissolved oxygen in water are very important in fish farming. Low oxygen is the number one problem of fish farmers since fish do not feed well at low oxygen concentration and the low oxygen content restricts the carrying capacity of the fish production ponds. Dissolved oxygen concentration of 5 ppm or higher are most desirable for catfish production, but successful fish operations are possible by maintaining oxygen concentrations of at least 4 ppm. Fish may survive oxygen concentrations as low as 0.5 ppm for short periods, but prolonged exposure to such low oxygen levels will result in fish kills or poor growth.
Oxygen depletion in a body of water can be restored by injecting dissolved oxygen at predetermined depths. This principle is well established by U.S. Pat. Nos. 3,956,432; 3,794,303 and 3,320,928, each of which teach the broad concept of utilizing a floatable base connected to an electric motor to pump air through a flexible plastic tube or other elongated tube anchored to the bottom of a pond or lake so as to pump dissolved oxygen into the lake in order to preserve fish, plant life, etc. In U.S. Pat. Nos. 3,626,901; 4,258,661 and 4,657,675, various techniques are employed for replenishing the amount of dissolved oxygen at a predetermined depth in a body of water, the latter two patents also teaching the use of a solar collector adapted to heat water in combination with a heat exchanger or the use of a solar electric energy powered motor which operates an air pump to introduce fresh air into a vertical column to replenish the dissolved oxygen in a body of water.
The prior art has also disclosed the use of a floatable base in conjunction with a water aeration system such as U.S. Pat. No. 3,626,901 which directs dissolved oxygen to a predetermined level in a body of water, while U.S. Pat. Nos. 3,521,864; 3,572,658 and 3,653,641 teach the use of a floatable base with an impeller to draw air and/or water from a body of water and disperse same at a predetermined distance from the floatable base along the surface of the water. Other water aeration devices, some of which disclose a floatable base are shown in U.S. Pat. Nos. 4,193,951; 4,268,398; 4,409,107; 4,215,082 and 4,308,137.
While it is apparent that the prior art is replete with various types of water aeration devices, most of the systems require extensive energy use and continued maintenance. Most of the prior art designs are also cumbersome and inefficient, requiring substantial investments without the possibility of delivering substantial quantities of vital dissolved oxygen at predetermined depths in a body of water.